Evaluation of volumetric strain quantities and types of volumetric strain curves under failure-deformation process of hard brittle rocks

Purpose. The aim of this work is to show whether or not a relationship exist among the different volumetric strain quantities and to assess also whether the volumetric quantities are related to the different types of volumetric strain curves under failure-deformation process of hard brittle rocks. Methods. Tests were conducted to determine the post failure stress-strain curves of different 83 rocks types under uniaxial compression using a closed loop servo-controlled testing system in accordance to ISRM (International Society for Rock Mechanics) suggested standards. Findings. The result show that the volumetric strains quantities are related by power form law. It was established that there is a connection between the volumetric strains quantities and the types of the volumetric strains curves. The first type volumetric strain curves contains the Class I and progress to Class II while the type three volumetric strain curves are entirely Class II rock. Originality. No experimental results have been published, which describe the connection between the type of volumetric strain curves and volumetric strain quantities or attempt to relate the volumetric strain quantities with type of post-failure stress-strain characteristic curves response of rocks under uniaxial compression. Most researchers in rock mechanics studies have so far been focused on the crack damage stress (σcd) and uniaxial compressive strength (σc) of characteristic stress levels during compression in which σcd = Ɛcd and σcd = σc to study deformation behavior of rocks. Practical implications. It was also observed that the difficulty in obtaining the post-failure curves increases from type one to type two and type three volumetric strain curves respectively. It could guide personnel conducting tests using closed-loop servo-controlled testing system, if dangerous situation or equipment damage could occur (especially with the third type deformation process) so that testing is performed safely. It could also be useful in understand-ding the total process of specimen deformation and estimation of the rocks brittleness (e.g. brittle for Class II and less brittle or ductile for Class I).Мета. Встановлення та оцінка взаємозв’язку між різними величинами та типами кривих об’ємної деформації у процесі одноосьового стиску жорстких крихких порід. Методика. Повні криві напруження й деформації визначалися при необмеженому одноосьовому випробуванні на стиск з використанням системи сервокерованого контролю із замкнутим контуром для оцінки механічних властивостей 83 різних типів порід (53 вивержених, 10 осадових і 20 метаморфічних). Процедури випробувань для визначення повних кривих напружень і деформацій гірських порід, а також параметрів їх міцності проводилися відповідно до запропонованого ISRM методу. Результати. Дослідження показали, що залежність величин об’ємної деформації описується степеневим законом. Встановлено, що існує зв’язок між величинами об’ємної деформації та типами кривих, що її описують. Перший тип кривих об’ємної деформації відповідає породам класу I з переходом до класу II, у той час як криві третього типу повністю відповідають породам класу II. Наукова новизна. Вперше експериментальним шляхом встановлено взаємозв’язок між типами кривих об’ємної деформації та її величиною. Зроблені перші спроби пов’язати величину об’ємної деформації з кривими напруження – деформації порід після руйнування при одноосьовому стиску, у той час як попередні результати отримані під час стиску. Практична значимість. Складність отримання кривих для стану породи після руйнування збільшується з переходом від 1 типу кривих об’ємної деформації до 2 і 3 типу, що є важливим аспектом для безпечного тестування порід персоналом. Результати роботи представляють інтерес для розуміння загальних процесів деформації зразка та оцінки крихкості порід (наприклад, крихкі породи класу II і менш крихкі або більш пластичні породи класу I).Цель. Установление и оценка взаимосвязи между различными величинами и типами кривых объемной деформации в процессе одноосного сжатия жестких хрупких пород. Методика. Полные кривые напряжения и деформации определялись при неограниченном одноосном испытании на сжатие с использованием системы сервоуправляемого контроля с замкнутым контуром для оценки механических свойств 83 различных типов пород (53 изверженных, 10 осадочных и 20 метаморфических). Процедуры испытаний для определения полных кривых напряжений и деформаций горных пород, а также параметров их прочности проводились в соответствии с предложенным ISRM методом. Результаты. Исследование показали, что зависимость величин объемной деформации описывается степенным законом. Установлено, что существует связь между величинами объемной деформации и типами описывающих ее кривых. Первый тип кривых объемной деформации соответствует породам класса I с переходом к классу II, в то время как кривые третьего типа полностью соответствуют породам класса II. Научная новизна. Впервые экспериментальным путем установлена взаимосвязь между типами кривых объемной деформации и ее величиной. Предприняты первые попытки связать величину объемной деформации с кривыми напряжения – деформации пород после разрушения при одноосном сжатии, в то время как предыдущие результаты получены во время сжатия. Практическая значимость. Сложность получения кривых для состояния породы после разрушения увеличивается по мере перехода от 1 типа кривых объемной деформации ко 2 и 3 типу, что является важным аспектом для безопасного тестирования пород персоналом. Результаты работы представляют интерес для понимания общих процессов деформации образца и оценки хрупкости пород (например, хрупкие породы класса II и менее хрупкие или более пластичные породы класса I).We appreciated Rock Engineering Department, Aalto University Helsinkin Finland for granting permission to determine the post-failure curves of the samples using their closed-loop servo-controlled machine

Writing Through the 4Cs in the Content Areas – Integrating Creativity, Critical Thinking, Collaboration and Communication

Writing is a complex process that involves a number of competences and a degree of imagination. It can be evolved by using the 4Cs in the content areas: integrating creativity, critical thinking, collaboration, and communication, all of which teachers have struggled to include as part of their curricula. These struggles are often caused by logistic and financial constraints. With the professional demand pressingly navigating towards technology, teachers can aid their students by applying solution amenable to immediate use, low cost and tolerates interdisciplinary implementation. The first step would be to abandon the conventional curricula that were taught before as most of the current students are at a whole new technological level. They can be replaced by more pertinent skills that cater to the artistic and professional outlooks of students. This will ultimately equip them to be able to meet the market standards and improve their vocational prospects

Challenges and solutions for Latin named entity recognition

Although spanning thousands of years and genres as diverse as liturgy, historiography, lyric and other forms of prose and poetry, the body of Latin texts is still relatively sparse compared to English. Data sparsity in Latin presents a number of challenges for traditional Named Entity Recognition techniques. Solving such challenges and enabling reliable Named Entity Recognition in Latin texts can facilitate many down-stream applications, from machine translation to digital historiography, enabling Classicists, historians, and archaeologists for instance, to track the relationships of historical persons, places, and groups on a large scale. This paper presents the first annotated corpus for evaluating Named Entity Recognition in Latin, as well as a fully supervised model that achieves over 90% F-score on a held-out test set, significantly outperforming a competitive baseline. We also present a novel active learning strategy that predicts how many and which sentences need to be annotated for named entities in order to attain a specified degree of accuracy when recognizing named entities automatically in a given text. This maximizes the productivity of annotators while simultaneously controlling quality

Design of Comminution Circuit for Optimum Performance of the Gravity Separation Unit at Itakpe Iron Ore Processing Plant, Nigeria

Designing an efficient and economic mineral processing plant begins with the choice of the best and most economic comminution circuit based on ore properties and concentrate end-user’s specifications. This is because crushing and grinding for preparation of suitable feed for the downstream processes are cost intensive. The Itakpe iron ore processing plant presently produces a taiing material containing up to 22% iron minerals mostly fines produced inevitably during comminution. This article analyzed the existing circuit and ore properties, and presents specific comminution tests that were undertaken in order to recommend an alternate and more effective circuit. Sieve analyses of the various products of the existing circuit were carried out. The results show that fines exist in the circuit as a result of the brittleness of some portions of the ore which leads to crumbling and sloughing of the material during crushing and handling. It is revealed that mechanical stacking and reclamation also contributes to the generation of fines in the circuit. One possibility to a solution is to screen the product of secondary crusher ahead of grinding with a +2mm coarse screen between the reclaimer and the primary autogenous mills to prevent further production of fines during crushing unless the downstream recovery process is entirely designed for flotation. This option however still allows much fine material to the concentration lines. It is therefore recommended that materials less than 2mm be screened off the products of primary and secondary crushers and treated separately in gravity or magnetic unit without grinding. A +2mm screen is also recommended for installation as control for the product of primary autogenous mills which should be treated for concentration in the gravity unit. If flotation is to be employed, a regrind mill will be installed on either or both of the concentration lines or to a blend of the two. Keywords: sloughing, crumbling, user’s specifications, hardness, dropping impact, iron-rich, brittlenes

Design of Comminution Circuit for Optimum Performance of the Gravity Separation Unit at Itakpe Iron Ore Processing Plant, Nigeria

Designing an efficient and economic mineral processing plant begins with the choice of the best and most economic comminution circuit based on ore properties and concentrate end-user’s specifications. This is because crushing and grinding for preparation of suitable feed for the downstream processes are cost intensive. The Itakpe iron ore processing plant presently produces a taiing material containing up to 22% iron minerals mostly fines produced inevitably during comminution. This article analyzed the existing circuit and ore properties, and presents specific comminution tests that were undertaken in order to recommend an alternate and more effective circuit. Sieve analyses of the various products of the existing circuit were carried out. The results show that fines exist in the circuit as a result of the brittleness of some portions of the ore which leads to crumbling and sloughing of the material during crushing and handling. It is revealed that mechanical stacking and reclamation also contributes to the generation of fines in the circuit. One possibility to a solution is to screen the product of secondary crusher ahead of grinding with a +2mm coarse screen between the reclaimer and the primary autogenous mills to prevent further production of fines during crushing unless the downstream recovery process is entirely designed for flotation. This option however still allows much fine material to the concentration lines. It is therefore recommended that materials less than 2mm be screened off the products of primary and secondary crushers and treated separately in gravity or magnetic unit without grinding. A +2mm screen is also recommended for installation as control for the product of primary autogenous mills which should be treated for concentration in the gravity unit. If flotation is to be employed, a regrind mill will be installed on either or both of the concentration lines or to a blend of the two. Keywords: sloughing, crumbling, user’s specifications, hardness, dropping impact, iron-rich, brittlenes

Design And Implementation of Android Based Voip System for Noise Pollution Control

Noise pollution happens to be a menace that the world is currently fighting hence, a way of controlling such pollution is needed so that in the event of passing information to a particular individual or group such information will land on the table of the recipient without constituting a menace to those around. The application of Information and Communication Technology ICT is therefore envisaged in solving this problem especially in environment where ICT is the order of the day. This paper, therefore, proposes a technological approach to solving this problem; the design and implementation of a Voice over Inter-Protocol VoIP as a means of sending voice messages from one android application to another, over a wireless network to individual, groups etc. The android platform was chosen because of its merit in portability and been able to connect to the internet easily. The VoIP has been designed, implemented and tested within the halls of residence of Covenant University, Nigeria and the result was satisfactory hence, acceptability of this work will show a great reduction in noise pollution in tertiary institutions, places of worships, and every other open spaces, events where messages need to be sent but to the specific recipient

Photoproduction of \eta mesons on protons in the resonance region:The background problem and the third S_11 resonance

We have constructed an isobar model for the $\eta$-photoproduction on the proton in the energy region up to the photon lab energy $K_0 = 3$ GeV. The data base involved into the fitting procedure includes precise results for the cross section and for the $T$-asymmetry of the process $\gamma p\to\eta p$ near threshold obtained at MAMI and ELSA as well as recent results for the $\Sigma$-asymmetry and for the angular distribution measured at higher energies in Grenoble and also more recent measurements performed at JLab for the photon energies up to 2 GeV. The model includes twelve nucleon resonances: $S_{11}(1535)$, $S_{11}(1650)$, $S_{11}(1825)$, $P_{11}(1440)$,$P_{13}(1720)$, $D_{13}(1520)$, $D_ {15}(1675)$, $F_{15}(1680)$, $F_{17}(1990)$,$G_{17}(2190)$, $G_{19} (2250)$, $H_{19}(2220)$, and the background consisting of the nucleon pole term and the vector meson exchange in the $t$-channel. To explain the observed energy dependence of the integrated cross section, two $s$ -wave resonances, $S_{11}(1650)$ and $S_{11}(1825)$, have to be taken into account along with the dominating $S_{11}(1535)$. The integrated cross section as well as the angular distribution and $\Sigma$ asymmetry predicted by the model are in good agreement with the data. Above the photon energy $K_0 = 2$ GeV, the calculated cross section exhibits an appreciable dependence on the $\rho$- and $\omega$-meson contribution, whose coupling with nucleons is not well defined. Several versions of extending the model to higher energies are considered.Comment: 7 pages, 8 figures, 2 tables, version to appear in Eur.Phys.J.A 22 (2004

Polyx multicrystalline silicon solar cells processed by PF+ 5 unanalysed ion implantation and rapid thermal annealing

Rapid thermal annealing of damage induced by implantation in silicon can be a cost effective technology for the processing of terrestrial solar cells as compared to classical furnace or pulsed laser annealing. Unfortunately, drawbacks as poor bulk lifetime or low open-circuit-voltage occur as well. We have attempted to overcome these limitations for POLYX multicrystalline cast silicon grown by CGE (France) by keeping the annealing temperature of the phosphorus doped layer as high as 800 °C (to ensure a good crystalline quality and a high dopant activation) while being less than 900 °C (to minimize the effect of degradation of the base properties). The purpose of the present work is to investigate the I-V characteristics of the cells and to compare to those obtained with classical furnace annealing or with classical diffusion process

Environmental Effects of Processing Marine Clay in Olotu, Ondo State, Nigeria

In this work, analysis of the released gas from calcined marine clay and lime shell was investigated. Study of the emitted gas/air from the calcined clay and shell showed that average concentration of carbon dioxide (CO2: 20.09PPM and 8.12PPM) are below the maximum standard natural concentration 600PPM of carbon dioxide in fresh air and the recommended World Health Organization Threshold Limit Value (TLV) of 500PPM. Average carbon monoxide (CO) concentration (0.004PPM, 0.010PPM) and sulfur dioxide (SO2) concentration (0.002PPM are below the Nigeria Ambient Air Quality Standards (NAAQS) and World Health Organization (WHO) maximum limit of 10PPM-20PPM (for carbon monoxide) and 0.01PPM- 0.5PPM (for sulfur dioxide) for an 8-hourly time. It was established that the average concentration of C0, C02, and S02 is so low and so pose no threat to the environment based on the review of the existing regulation, standards and codes (WHO and NAAQSO). Keywords: Ambient, Testo 350XL- Analyzer, PPM- Part Per Million, calcinin

Study of polarization observables in double pion photoproduction on the proton

Using a model for two pion photoproduction on the proton previously tested in total cross sections and invariant mass distributions, we evaluate here polarization observables on which recent experiments are providing new information. We evaluate cross sections for spin 1/2 and 3/2, which are measured at Mainz and play an important role in tests of the GHD sum rule. We also evaluate the proton polarization asymmetry $\Sigma$ which is currently under investigation at GRAAL in Grenoble.Comment: 23 pages, 14 ps figure